House intelligence committee sources say career officials at the National Security Council are slow-walking the delivery of subpoenaed records on former National Security Adviser Susan E. Rice’s handling of classified information and the “unmasking” of Trump campaign workers — material from the Russian hacking probe that middle-level NSC managers claim was transferred to President Obama’s library and could “remain closed to the public for five years.”

Tom Fitton, president of the legal activist group Judicial Watch, said the sealing of unmasking records was an example of how U.S. intelligence agencies are stonewalling.

It was first revealed in a recent Freedom of Information Act exchange between Judicial Watch and the NCS that the records had been moved to the Obama library’s secure archive.

“Having to subpoena this information indicates the insanity of the situation when the nation’s top intelligence agencies are withholding information — basic information — that could bring to an end the controversy raging across this country,” Mr. Fitton said in an interview Thursday.